The invention relates to a cathode sputtering system with at least one cathode station, which is encased by an outer shell and designed as a vacuum chamber and has at least one cathode with a target. A substrate holder is located in this cathode station in order to hold a substrate that is to be coated, such as for instance a data storage diskette, and this cathode station has at least one gas inlet and at least one gas outlet that is to be connected to a vacuum pump.
A cathode sputtering system of this type is described in U.S. Pat. No. 4,558,388, which is incorporated herein by reference. In the case of this system, a substrate is being held in the center of the cathode station on an axis, and a cathode with a target is located on either side of the substrate in order to coat both sides of the substrate simultaneously by means of a sputtering process. In order to produce the required vacuum, a gas outlet is provided in the outer casing of the cathode station in a direction perpendicular to the axis. This gas outlet runs through the cathode and is connected to a vacuum pump. The gas inlet is located above the cathode on one front side of the outer casing. Usually substrates have to be coated extremely evenly. When dealing with data storage disks, the thickness of the aluminum layer applied must for instance be less than one ten-thousandth of a millimeter. An uneven coating would lead to a decrease in storage locations for the digital information that needs to be stored.
In order to achieve the desired evenness in the coating, measures were primarily taken in the case of known cathode sputtering systems to ensure that the substrate is oriented exactly toward the cathode and the target and that the physical conditions influencing the progression of the sputtering process are optimized and kept as constant as possible.